Consider the following quote from the official JBoss documentation (available at https://docs.jboss.org/jbossas/docs/Getting_Started_Guide/4/html-single/index.html):
If we find an open instance of JBoss with unauthenticated access to the JMX console, we can upload the shell to the server using the MainDeployer option. This allows us to fetch a WAR file from a URL and deploy it on the server. The JMX console is shown in the ...